fix: don't add empty id/authors (#1052)

Author: Disservin

app/src/game/pgn/pgn_builder.cpp

@@ -34,10 +34,18 @@ PgnBuilder::PgnBuilder(const config::Pgn& pgn_config, const MatchData& match, st
     pgn_generator_.addHeader("Result", getResultFromWhiteMatch(white_player));
 
     if (!pgn_config_.min) {
-        pgn_generator_.addHeader("EngineWhiteName", white_player.uci_name);
-        pgn_generator_.addHeader("EngineWhiteAuthor", white_player.uci_author);
-        pgn_generator_.addHeader("EngineBlackName", black_player.uci_name);
-        pgn_generator_.addHeader("EngineBlackAuthor", black_player.uci_author);
+        if (!white_player.uci_name.empty()) {
+            pgn_generator_.addHeader("EngineWhiteName", white_player.uci_name);
+        }
+        if (!white_player.uci_author.empty()) {
+            pgn_generator_.addHeader("EngineWhiteAuthor", white_player.uci_author);
+        }
+        if (!black_player.uci_name.empty()) {
+            pgn_generator_.addHeader("EngineBlackName", black_player.uci_name);
+        }
+        if (!black_player.uci_author.empty()) {
+            pgn_generator_.addHeader("EngineBlackAuthor", black_player.uci_author);
+        }
     }
 
     if (match_.fen != chess::constants::STARTPOS || is_frc_variant) {

app/tests/pgn_builder_test.cpp

@@ -56,6 +56,22 @@ Nf6 {+10.15/18 1.821s, engine2 got checkmated} 1-0
         CHECK(pgn_builder.get() == expected);
     }
 
+    TEST_CASE("PGN omits empty UCI identity tags") {
+        MatchData match_data;
+        match_data.players.white.config.name = "engine1";
+        match_data.players.white.uci_name    = "Engine One";
+        match_data.players.black.config.name = "engine2";
+        match_data.players.black.uci_author  = "Author Two";
+        match_data.fen                       = chess::constants::STARTPOS;
+
+        const auto pgn = pgn::PgnBuilder(config::Pgn{}, match_data, 1).get();
+
+        CHECK(pgn.find("[EngineWhiteName \"Engine One\"]") != std::string::npos);
+        CHECK(pgn.find("EngineWhiteAuthor") == std::string::npos);
+        CHECK(pgn.find("EngineBlackName") == std::string::npos);
+        CHECK(pgn.find("[EngineBlackAuthor \"Author Two\"]") != std::string::npos);
+    }
+
     TEST_CASE("PGN Creation Black Win") {
         MatchData match_data;
         match_data.players.white.config.name = "engine1";